This invention relates to an electrically power assisted bicycle and more particularly to an improved bicycle of this type, a transmission arrangement for the engine and a one way clutch and bearing assembly therefore.
Electrically power assisted bicycles of the type shown in my U.S. Pat. No. 5,266,501, issued Jul. 13, 1993 and my applications, Ser. Nos. 08/026,868 filed Mar. 5, 1993, now issued as U.S. Pat. No. 5,375,676 on Dec. 27, 1994; 08/059,540 filed Mar. 10, 1993 now issued as U.S. Pat. No. 5,370,200 on Dec. 6, 1999; and 08/128,866 filed Sep. 29, 1993 now U.S. Pat. No. 5,474,148, all of which are assigned to the assignee hereof, have a number of advantages. In the construction shown in each of those applications and the aforenoted patent, the bicycle is provided with a conventional pedal mechanism operated by the rider.
In addition, there is provided an electric motor powered by a battery and controller arrangement for assisting the operator effort in response to the pedal input force so as to make the riding of the bicycle easier while at the same time maintaining its ability to provide exercise for the rider. In the connection between the electric motor and the driven rear wheel of the bicycle, it is the practice to incorporate a gear reduction unit so as to reduce the speed and increase the power output of the electric motor for transmission to the driven wheel. As disclosed in my aforenoted application, Ser. No. 08/026,868, now U.S. Pat. No. 5,375,676 the disclosure of which is incorporated herein by reference, a planetary transmission is employed between the motor output shaft and the drive for the rear wheel so as to provide this speed reduction. Although this type of arrangement is extremely effective, the stacked electric motor and transmission somewhat increases the length of the electric drive and also the use of a separate motor and transmission requires alignment of the component to insure smooth operation.
It is, therefore, a principal object to this invention to provide an improved electric motor and transmission assembly for powering devices such as bicycles.
It is a further object to this invention to provide an electric motor and transmission combination which may provide a compact assembly.
It is a further object to this invention to provide an improved electric motor and transmission wherein assembly is facilitated and self alignment is possible.
In conjunction with the use of an electric motor for assisted power of a bicycle, it is the general practice, as disclosed in the aforenoted copending applications and patent that one way clutches are interposed between both the electric motor and the rear wheel and between the crank mechanism and the rear wheel drive so as to facilitate the transmission of power and not to transmit power to portions which should not be driven. The use of one way clutches requires a pair of elements with one way clutching elements interposed between them. The two elements that are interconnected by the one way clutching elements must be maintained so that their axes of rotation are substantially coincident and it is the normal practice to employ a bearing arrangement for this purpose. This obviously adds to the cost and complexity of the arrangement.
It is, therefore, a still further object to this invention to provide an improved and simplified one way clutch assembly for use with various drives including those for electric motor assisted bicycles.